1. Field of the Invention
This invention relates to a ferroelectric liquid crystal element, and more particularly to a nonspirally-aligned ferroelectric liquid crystal element producing two different orientation states when no electric field is applied.
2. Description of the Prior Art
N. A. Clark et al. have disclosed (for example, in U.S. Pat. No. 4,367,924 and U.S. Pat. No. 4,563,059) the production of a liquid crystal element capable of two different stable orientation states (bistability) when no electric field is applied so as to provide a memory capability by disposing a ferroelectric smectic liquid crystal (chiral smectic C or H liquid crystal) producing a spiral alignment structure in bulk state between a substrate spacing which is small enough to suppress the spiral alignment structure thereof.
N. A. Clark et al. use the application of magnetic field or shearing in order to realize the above-described bistable orientation state, but it is more practical to use rubbing or oblique evaporation processing as an orientation processing procedure. A liquid crystal element in which rubbing or oblique evaporation processing has been utilized in order to realize a bistable orientation state having a monodomain has been disclosed, for example, by S. Okada et al. in U.S. Pat. No. 4,639,089.
However, ferroelectric smectic liquid crystal having a bistable orientation state with a monodomain realized by rubbing or oblique evaporation processing has a disadvantage that the amount of transmission light under memory state is less that of N. A. Clark et al.
Accordingly, the present inventor has investigated the possibility of realizing a novel bistable orientation state which produces the same degree of optical modulation effect produced from a bistable orientation state as that realized by N. A. Clark et al. by adopting more practical rubbing or oblique evaporation processing as an orientation processing means.